Loading...

Optimization of the Capability of Native Microorganisms Isolated from the Landfill of Electronic Wastes in Bioleaching of E-Waste

Arab, Bahareh | 2019

511 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52577 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Yaghmaei, Soheila
  7. Abstract:
  8. Given the complex structure of electronic waste and the difficulty of recycling it by traditional methods, the focus is mainly on biohydrometallurgy method, and in particular on bioleaching. To recover metals, various microorganisms are utilized in this method. In light of previous studies, cyanogenic bacteria have been widely used for the extraction of basic and precious metals. Among the species, indigenous microorganisms have a higher ability to resist toxic environments in the bioleaching of metals due to their adaptation by rapid changes in their metabolic system over time. The main objective of this study is to isolate indigenous microorganisms from electronic waste landfill for their use in copper bioleaching. Another objective of this study is to optimize the effective factors in this process to achieve the maximum recovery of this metal. In this regard, by collecting two different soil samples from two separate e-waste landfills and isolating their microbial populations, 94 bacterial strains were purified out of which 17 species of cyanogen were identified. By evaluating their ability to produce metabolites effective in bioleaching, 5 species with higher potency were selected. Then the factors affecting cyanide production, including initial pH, glycine concentration, and temperature were optimized for each bacterium using the one factor at a time method. An initial pH of 7, a glycine concentration of 2 g/L and a temperature of 30° C were obtained as the optimum conditions for most bacteria. Finally, the extraction of copper metal at a pulp density of 1 g/L and in two states with and without applying optimum conditions was investigated by indigenous cyanogenic bacteria. At optimum conditions, recovery rates of 96.73%, 82.49%, 81.17%, 41.72%, and 31.52% were recorded which were increased by 1.5-5 times compared to non-optimal recovery conditions
  9. Keywords:
  10. Electronic Waste ; Bioleaching ; Optimization ; Indigenous Microorganism ; Cyanogenic Bacterias ; Copper Extraction ; Indigenous Microorganism Isolation

 Digital Object List

 Bookmark

No TOC